#!/bin/sh
#
# Part of Gerrit Code Review (http://code.google.com/p/gerrit/)
#
# Copyright (C) 2009 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

usage() {
  echo >&2 "usage: $0 remote changeid..."
  echo >&2 "usage: $0 --continue"
  echo >&2 "usage: $0 --skip"
  echo >&2 "usage: $0 --abort"
  echo >&2 "usage: $0 [--close|--replace] remote"
  exit 1
}

die() {
  echo >&2 "fatal: $1"
  exit 1
}

GIT_DIR=$(git rev-parse --git-dir) || exit
CL="$GIT_DIR/GERRIT_CHANGES"
STATE="$GIT_DIR/rebase-gerrit"
TODO="$STATE/todo"

RESOLVEMSG="
When you have resolved this problem run \"$0 --continue\".
If you would prefer to skip this patch, run \"$0 --skip\".
"

pop_action() {
  sed -e 1d <"$TODO" >>"$TODO".new
  mv -f "$TODO".new "$TODO"
}

mark_done() {
  read commit changeid <"$TODO"
  changeid=$(get_changeid "$changeid")
  head_after=$(git rev-parse HEAD^0)
  head_before=$(cat "$STATE/head_before")
  if ! test $head_after = $head_before
  then
    echo $head_after >"$CL/$changeid"
  fi
  pop_action
}

do_next() {
  while test -s "$TODO"
  do
    read commit changeid <"$TODO"
    git rev-parse HEAD^0 >"$STATE/head_before"
    git format-patch \
        -k --stdout --full-index --ignore-if-in-upstream \
        $commit^..$commit |
    git am $git_am_opt --rebasing --resolvemsg="$RESOLVEMSG" || exit
    mark_done
  done

  echo >&2 "Done."
  rm -rf "$STATE"
}

git_am_opt=
if test -f "$STATE/git_am_opt"
then
  git_am_opt=$(cat "$STATE/git_am_opt")
fi

while test $# != 0
do
  case "$1" in
  --continue)
    test -f "$TODO" || die "No cherry-pick in progress?"
    git am $git_am_opt --rebasing --resolvemsg="$RESOLVEMSG" --resolved || exit
    mark_done
    do_next
    exit
    ;;
  --skip)
    test -f "$TODO" || die "No cherry-pick in progress?"
    git reset --hard HEAD || exit
    git am --skip || exit
    pop_action
    do_next
    exit
    ;;
  --abort)
    test -f "$TODO" || die "No cherry-pick in progress?"
    git reset --hard HEAD
    git am --skip
    rm -rf "$STATE"
    ;;
  --close|--replace)
    shift
    test -d "$CL" || die "No changes to close"
    test $# = 1   || usage
    remote=$1
    printf %s "git push $remote" >&2
    rs=$(cd "$CL" && for change_id in *; do
      test "$change_id" = '*' && die "No changes to close"
      c=$(cat "$change_id");
      echo "$c:refs/changes/$change_id";
      echo ' \' >&2;
      printf %s "  $c:refs/changes/$change_id" >&2
      done)
    echo >&2
    echo >&2
    git push $remote $rs
    rc=$?
    test $rc = 0 && rm -rf "$CL"
    exit $rc
    ;;
  --whitespace=*)
    git_am_opt="$git_am_opt $1"
    ;;
  --committer-date-is-author-date|--ignore-date)
    git_am_opt="$git_am_opt $1"
    ;;
  -C*)
    git_am_opt="$git_am_opt $1"
    ;;
  -s|--signoff)
    git_am_opt="$git_am_opt $1"
    ;;
  -*)
    usage
    ;;
  *)
    break
    ;;
  esac
  shift
done

get_changeid() {
  case $1 in
  */*) echo ${1%%/*} ;;
  *)   echo $1 ;;
  esac
}

to_ref() {
  case $1 in
  */*)
    change_id=${1%%/*}
    patchset_id=${1##*/}
    ;;
  *)
    change_id=$1
    patchset_id=1
    ;;
  esac

  hash=$(($change_id % 100))
  case $hash in
  [0-9]) hash="0$hash" ;;
  esac

  echo "refs/changes/$hash/$change_id/$patchset_id"
}

get_revid() {
  grep $(to_ref $1) <"$GIT_DIR/FETCH_HEAD" | cut -f1
}

# Initialize state
#
test $# -lt 2 && usage
remote="$1"
shift

mkdir "$STATE" || die "cherry-pick already in progress"
echo $git_am_opt >"$STATE/git_am_opt"

if ! git fetch $remote $(for id; do to_ref $id; done)
then
  rm -rf $STATE
  exit 1
fi

(for id
 do
  if revid=$(get_revid $id)
  then
    echo "$revid $id"
  else
    echo >&2 "fatal: $id not found"
    exit 1
  fi
done) >"$TODO"

mkdir -p "$CL"
echo >&2
do_next